Troop ordered into active military service 15 December 1942 and reorganized at Camp Howze, Texas, as the 86th Cavalry Reconnaissance Troop, an element of the 86th Infantry Division

Reorganized and redesignated 5 August 1943 as the 86th Reconnaissance Troop, Mechanized

Reorganized and redesignated 10 October 1945 as the 86th Mechanized Reconnaissance Troop

Inactivated 30 December 1946 in the Philippine Islands

(Organized Reserves redesignated 25 March 1948 as the Organized Reserve Corps; redesignated 9 July 1952 as the Army Reserve)

3d Platoon, 86th Mechanized Reconnaissance Troop, converted and redesignated
20 May 1963 as Headquarters and Headquarters Company, 172d Infantry Brigade, and relieved from assignment to the 86th Infantry Division; concurrently withdrawn from the Army Reserve and allotted to the Regular Army (remainder of troop – hereafter separate lineage)